I did a whole laundry list of tweaks. I designed and tested a better filament drive. I shortened my bowden tube. I decreased the current for the steppers. I added a spool holder. I am going to see if I can get calibration going tonight to enable full bed prints. It doesn't sound like much now that I list it but as lazy as I am it took a ton of Twilight Zone episodes to get it done.

I hope to switch over to the 7/16" screws or make a new LISA with the 7/16" screws soon.

Hey Nicholas, I'm a long time lurker, I've been watching your designs and progress almost daily since the original Simpson Gada prize design. Anyway, I love the elegance and purity of the engineering for the whole Simpson family.

In relation to the LISA Simpson I was wondering what you think the improvements over a standard delta (Rostock, etc...) are? RepRap-ability is clearly one, but how do they compare on price, performance, or any other metric you can think of.

I originally didn't see much value to this design but figured it would be a fun build for my students. It is almost an oxymoron. Simpson's are suppose to be free of linear motion. I have since broadened my internal definition of a Simpson to be a delta robot with no spherical joints.

Here are some points when comparing it to a Rostock style bot.Pros:[*]Simplicity[*]Maintainability[*]Easy to RepStrap[*]Easy to assemble[*]No spherical joints[*]Possibly cost but not yet.

Cons:[*]Less rigid (It is easier to twist the hub.)[*]Speed (I have been able to go faster than my filament drive can go.)[*]Cost (The screws are pricey but now that I have verified the design I will try to make a RepStrap with super cheap components. I just need to hit 60mm/s to be acceptable.)

I actually view LISA as two systems. The screw drive and the arms. You could use the arms with a belt /rail setup and you can use the screw drive with Rostock arms. Since LISA can get away with one long metal thing per arm I thought I would test out the screws with the Simpson style arms.

After playing with LISA for a while, I prefer the ease of maintenance of the screws over the filament drives. Even if I can't get the cost down (which I should be able to) I think many will see that the extra cost is worth it.